Soothing

Pronunciation:ˈsuːðɪŋ

Kind of word: Adjective

Formal definition: having a gently calming effect.

Informal definition: be relax.

Example: 
 

- The tone and rhythm of your voice are soothing.

Synonym:

• soothing
• calming
• sedative
• calmative
• pacificatory
•  reposeful

Song or video: 

https://www.youtube.com/watch?v=W7PXVBwfIg8

Another link:

 http://www.wordreference.com/es/translation.asp?tranword=soothing

Riveting

pronunciation: ˈrɪvɪtɪŋ

kind of word: Adjective

Formal definition: completely engrossing

Informal definition: something that you like it.

Example:

- it´s a riverting book.

Synonym: 

• fascinating  
• gripping
• engrossing
• interesting
• intriguing

Song or video:

https://www.youtube.com/watch?v=ekjIDGmvge8

Another link:

http://www.wordreference.com/es/translation.asp?tranword=riveting

Monotonous

Pronunciation: məˈnɒtənəs

Kind of word: Adjective
 

Formal definition: dull, tedious, and repetitious; lacking in variety and interest.

 
Informal definition: Something that is boring.

Example:

- His voice was monotonous , expressionless and cold.

Synonym:

• monotone
•  drab
• dreary
•  humdrum
• singsong

Song or video:

https://www.youtube.com/watch?v=PqEQWC_6yYQ

Another link:

https://www.youtube.com/watch?v=lrqwZqJEPWE